Subbing photographic film



March 1, 1955 w. R. WHITE ET Al. 2,703,284

SUBBINGPHOTOGRAPHIC FILM Filed Feb. 8, 1951 GE AT/N CHI. ULOSE E575? BASE ,auf f /VAof/qz/ @r MUM/E WH/f nventors Gttomegs United States Patent() "ce,

SUBBIN G PHOTOGRAPHIC FILM Walter R. White and Gale F. Nadeau, Rochester, N. Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application February 8, 1951, Serial No. 210,055

Claims. (Cl. 95-9) This invention relates to a method of subbing photographic film in which the polymerized mixture of a lower fatty acid ester of cellulose and an alkyl acrylate 1s em ployed as the subbing layer.

Various materials have been suggested as subblng agents in the making of photographic film. Some subbing agents which have been suggested have been poor 1n adhesiveness, others when in use exhibit brittle characteristics, others have shown properties characterized by .a changing in position of the emulsion on photographlc film with reference to the rest of the film, known as skidding One object of our invention is to provide a method .of subbing photographic film to contribute to the flexibility thereof.V Another object of our invention is to provide a method of subbing photographic film in which any skidding of the layers therein is reduced to a minimum. A further object of our invention is to employ as a subbing layer for photographic lm the polymerized mixture of a lower fatty acid ester of cellulose and an alkyl acrylate. Other objects of our invention will appear herein.

We have found that subbing layers essentially consisting of a polymerized mixture of a lower fatty acid ester of cellulose and an alkyl acrylate provide good adhesiveness, prevent skidding of the emulsion thereon, contribute to the flexibility of the film and are also readily adapted to use for subbing purposes.

The accompanying drawing illustrates an enlarged sectional view of a photographic film base containing a subbing layer according to our invention;l the figure being the sectional view of a cellulose ester lm base subbed with successive layers of (1) the polymerized mixture of a fatty acid ester of cellulose and an alkyl acrylate, (2) cellulose nitrate, and (3) gelatin. By applying a layer of the photographic emulsion thereonr over the gelatin coating, there is obtained a completed photographic film.

The subbing layer, in accordance with our invention, may be prepared from a polymerized mixture in which has been used any of the lower fatty acid esters of cellulose such as cellulose tripropionate, cellulose acetate butyrate, cellulose acetate, or any of the esters of cellulose and a fatty acid of 2 to 4 carbon atoms. The alkyl acrylate used may be ethyl acrylate,` methyl acrylate, methyl methacrylate, or the like.

A polymerized mixture of a lower fatty acid ester of cellulose and the alkyl acrylate is conveniently prepared in the following manner:

A slurry is prepared of the cellulose ester, in a very finely divided or powder form, in water using a wetting agent. There is then mixed therewith an emulsion of the alkyl acrylate in water together with an emulsifier, a catalyst, and any other modifying materials desired. These compositions may be prepared as follows:

Parts l. Alkyl acrylate 23 Water 48 Acetyl peroxide 0.5

A higher sodium alkyl sulfate, the alkyl being of the order of C14 known as Tergitol penetrant No. 4 in the form of its 30% aqueous solution-- 0.7

Sodium bisulte .l1 2. Cellulose ester Water 40 Tergitol penetrant No. 4 in the form of its 30% aqueous solution 0.2

known for film base purposes.

2,703,284 Patented Mar. l, 1955 After these two compositions have been thoroughly mixed, the mixture is polymerized by tumbling it at 55 C. for three (3) days. The product obtained is then liltered, washed, and dried. This product is soluble in acetone, ethylene chloride and other organic solvents.

A polymerized mixture of cellulose ester and alkyl acrylate may be obtained by dissolving the cellulose ester in the acrylate, preferably in the proportions of 20-40% of the cellulose ester and 80-60% of the acrylate. The solution thus obtained is then dispersed in a composition of water and an emulsiiier. The emulsier may be a material such as gum arabic, polyvinyl alcohol, or some other similar dispersing material, such that the acrylate containing the cellulose ester may be uniformly dispersed in the water. The acrylate solution is conveniently dispersed in Water in the proportions of 3 parts of Water to l part of the acrylate solution, although greater dilutions may be advantageously employed if desired. Also, incorporated in the mass is a small proportion of a peroxide catalyst such as benzoyl peroxide. The polymerization is carried out by employing an elevated temperature such as 60 to 80 C. for the time found desirable to give the necessary polymerization. Ordinarily, 24 hours is adequate although other times may be used such as within the range of 6-48 hours. There results in this polymerization beads which may be easily dispersed by dissolving in an organic solvent such as acetone, ethylene chloride, and the like, or their mixtures. If desired, additional cellulose ester may be added to the polymerized mixture used for the subbing layer.

The cellulose ester which is employed as the film base may be a hydrolyzed cellulose acetate, a substantially fully esterited cellulose acetate, ordinarily known as triacetate, or a mixed ester of cellulose, such as cellulose acetate propionate, or cellulose acetate butyrate, all as are A subbing layer as described herein may be applied directly to the lm base and, if desired, a subbing layer of subbing-type cellulose nitrate may be applied thereover. There may then be v y applied a layer of photographic emulsion, but preferably a layer of gelatin is first applied followed by the application of a layer of photographic emulsion thereover. Instead of employing separate layers of cellulose nitrate and gelatin prior to applying the emulsion layer, the cellulose nitrate and the gelatin are conveniently mixed together and applied as one layer to the film having the subbing layer thereon in accordance with our invention. For instance, a composition of the following proportions may be employed in applying this layer:

Per cent Gelatin 1.2 Cellulose nitrate-- 0.3 CrCl3.6H2O 1.5% of the weight of the gelatin employed. Water 5.0 Acetone 65 Methanol the balance of the composition.

'Ihe application of this material may be by any recognized means of applying thin layers to film base. The application of this coating may be by means of rollers, brushes, air-knife, blades, sprays, or by any similar method which will apply the subbing coating to the iilm base in the form of a thin uniform layer without adversely affecting its properties. Whereas, With some types of subbing layers when the sensitized photographic film is incubated at C. for 10 minutes, the emulsion skids so that the edges of the emulsion and of the film base may be as much as .020 inch apart, we have found that by employing as the subbing layer a product in which the cellulose ester and the acrylate are mixed together prior to polymerization thatl a photographic film is obtained which exhibits no skidding properties. We have also found that such a film exhibits properties more advantageous than are obtained by using as the subbing layer a physical mixture of the polymerized acrylate and the cellulose ester. The product so-obtained when coated with the usual gelatino-silver halide emulsion is found to have good flexibility and free of any skidding characteristics.

The following examples illustrate our invention:

Example 1.-30 parts of cellulose tripropionate was dissolved in 70 parts of monomeric ethyl acrylate and the resultant solution was dispersed in water with agitation in the proportion of 1 part of solution to 3 parts of water, said water also containing a small amount of gum arabic to assist in the dispersing' operation. .05 part of benzoyl peroxide was also incorporated therein. The mass was polymerized by heating at 60 to 80 C. for 24 hours. The polymer was obtained in bead form and was knownas resin A.

3% of resin A was formed into a solutionusing 58% ethylene chloride, 5.5% ethyl acetate, and 33.5% acetone. This solution was coatedonto a film support of cellulose triacetate plasticized with triphenyl phosphate to form a subbing layer of resin A thereon. There was then applied a coating of a cellulose nitrate layer from a solution o 2.25% cellulose nitrate in methyl alcohol which contained 5% butyl alcohol. thin layer of a solution containing 0.9% gelatin' in a solvent consisting of 1% glacial acetic acid, 15% water, and the balance methyl alcohol. As a check, a sample of the film base was subbed with a mixture of gelatin and cellulose nitrate followed by a layer of gelatin but without the subbing layer as described herein. The two samples were then coated with a photographic emulsion and were tested. It was found that the sample with the subbing layer as described herein tolerated much greater creasing before breaking occurred than the sample without that subbing layer. Also, when the lm was suddenly compressed between the fingers after heating in an oven at 90 C. for 10 minutes, that in the case of the film in accordance with our invention, even though the emulsion had cracked, the support remained intact, whereas with the other sample, complete breaking of both emulsion and support occurred. The exibility of the lrn in accordance with our invention, using the subbing layer as described, is far superior to that of the film in which that layer is not used. Both samples were found to be satisfactory as regards skidding of the emulsion and as regards adherence of the emulsion to the film.

Example 2.-A resin as described in the l`preceding example was formed into a solution using 58% ethylene chloride, 5.5% ethyl acetate and 33.5% of acetone and the solution was coated onto lm support of plasticzed cellulose triacetate. There was then applied thereto a thin coating of a mixture of gelatin and cellulose nitrate from a composition having the following proportions:

Gelatin 1.2%.

Cellulose nitrate 0.3%.

CrCla.6H2O 1.5% of the weight of the gelatin.

Water 5.0%.

Acetone 65%.

Methanol the balance.

After this layer had been applied and dried, the lm so-subbed was then coated with a photographic emulsion There was then applied thereover a layer and dried. The photographic lm thus prepared was tolerant of lsevere creasing before any breaking occurred and any breaking which did occur was of the emulsion layer.

We claim:

1. A photographic ilm comprising a support of a lower fatty acid ester of cellulose, a subbing layer thereon essentially consisting of the material which results from heating an aqueous dispersion of a mixture of 1Z0-40% of 'a cellulose ester and 80-60% of an alkyl acrylate containing a peroxide catalyst, and a silver halide-gelatin photographic emulsion layer.

2. A photographic film comprising a support of cellulose triacetate, a subbing layer thereon essentially consisting of the material which results from heating an aqueous dispersion of a mixture of 20*40% of a lower fatty acid ester of cellulose and 80-60% of an alkyl acrylate containing a peroxide catalyst, and a silver halidegelatin photographic emulsion.

3. A photographic film comprising a cellulose acetate support, a subbing layer thereon essentially consisting of the material which results from heating an aqueous dispersion of a mixture of 20-40% of cellulose tripropionate and 80-60% of ethyl acrylate containing a peroxide catalyst, and a silver halide-gelatin photographic emulsion ayer.

4. A photographic film comprising a cellulose organic ester support and in order thereon a subbing layer essentially consisting of the material which results from heating an aqueous dispersion of a mixture of 20-40% of a lower fatty acid ester of cellulose and 80-60% of an alkyl acrylate containing a peroxide catalyst, a cellulose nitrate layer, a gelatin layer and a silver halide-gelatin photographic emulsion layer.

5. A photographic film comprising a cellulose organic ester support and Vin order thereon a subbing layer essentially consisting of the material which results from heating an aqueous dispersion of a mixture of 20-40% of a cellulose e'ster kand 80-60% of an alkyl acrylate containing a peroxide catalyst, a layer of a mixture of gelatin and cellulose nitrate and a silver halide-gelatin photographic emulsion layer.

References Cited in the le of this patent UNITED STATES PATENTS 1,933,052 Fikentscher et al. Oct. 31, 1933 2,110,496 Babcock Mar. 8, 1938 2,171,7 Rohm Sept. 5, 1939 2,186,454 Gloor Jan. 9, 1940 2,196,775 McNally Apr. 9, 1940 2,271,228 Nadeau et a1. Ian. 27, 1942 2,292,393 Mitchell Aug. 11, 1942 FOREIGN PATENTS 487.795 Great Britain June 24, 1938 

1. A PHOTOGRAPHIC FILM COMPRISING A SUPPORT OF A LOWER FATTY ACID ESTER OF CELLULOSE, A SUBBING LAYER THEREON ESSENTIALLY CONSISTING OF THE MATERIAL WHICH RESULTS FROM HEATING AN AQUEOUS DISPERSION OF A MIXTURE OF 20-40% OF A CELLULOSE ESTER AND 80-60% OF AN ALKYL ACRYLATE CONTAINING A PEROXIDE CATALYST, AND A SILVER HALIDE-GELATIN PHOTOGRAPHIC EMULSION LAYER. 